Predicting crack growth resistance of aluminium sheets

The Gurson–Tvergaard–Needleman and the cohesive zone models are applied for modelling the ductile crack growth in thin aluminium sheets under monotonic loading. The material’s yield curve is obtained by standard tensile tests, whereas the remaining model parameters are fitted for a Kahn specimen. The transferability of these parameters from the small Kahn specimen to large centre-cracked panels is shown through numerical simulations. Both models were successfully applied to simulate the fracture resistance of a specimen, showing their ability to describe crack propagation of thin metal sheet. The effects of varying mechanical properties on fracture resistance are demonstrated by parameter studies. However, the transition from flat to slant fracture observed in real tests is not modelled at this stage. This requires rather laborious 3D calculations.